A known blow-by gas reflux apparatus reintroduces to an internal combustion engine by way an intake manifold, and burns, gases that flow through a gap between a piston and a cylinder wall surface of the internal combustion engine into a crankcase without allowing the gases to be released into the atmosphere. For example, patent document 1 discloses a blow-by reflux apparatus that includes a first positive crankcase ventilation (PCV) passage connecting a cylinder head and an intake passage of the internal combustion engine, a second PCV passage connecting a portion of the intake passage downstream of a connection between the first PCV passage and the cylinder head, and a PCV valve disposed at the second PCV passage. The blow-by gas reflux apparatus uses pressure inside the intake manifold (intake manifold pressure) that is a negative pressure. The blow-by gas reflux apparatus introduces the blow-by gas from the crankcase to the first PCV passage and, at the same time, introduces fresh air from the second PCV passage to the crankcase to thereby ventilate the crankcase.
In addition, an exhaust gas recirculation (EGR) apparatus is known wherein part of exhaust is introduced to the intake manifold and mixed with intake air. Patent document 2, for example, discloses a supercharged internal combustion engine including an EGR apparatus. The supercharged internal combustion engine includes an EGR passage that connects an exhaust passage upstream of an exhaust turbine and an intake passage downstream of a compressor, an ejector disposed on the EGR passage, and a connecting passage that connects a portion of the intake passage upstream of a connection between the intake passage and the EGR passage and the ejector. In the supercharged internal combustion engine, the ejector is disposed such that a nozzle portion thereof is upstream (specifically, on the exhaust passage side) of the EGR passage and a diffuser portion thereof is downstream (specifically, on the intake passage side) of the EGR passage. When an EGR gas is introduced, therefore, the EGR gas flowing through the ejector allows the intake air in the connecting passage to be drawn into the EGR passage, so that a flow rate of intake air introduced to the intake manifold can be increased.